Sensitivities of Australian and New Zealand amphipods to copper and zinc in waters and metal-spiked sediments

The sensitivities of eight benthic amphipods, Chaetocorophium cf. lucasi, Corophium colo, Grandidierella japonica, Hyale crassicornis, Hyale longicornis, Melita awa, Melita matilda and Melita plumulosa, to copper and zinc in water-only and whole-sediment toxicity tests were compared. Whole-sediment tests used copper- (1300 mg/kg) and zinc- (4000 mg/kg) spiked sediments after equilibration for sufficient time to produce pore water and overlying water concentrations below the lowest observable effect concentrations of water-only exposures. Survival of adults (after 10 d) and juveniles (after 96 h), and the metal concentrations in the body tissues of adults, were determined at the end of the tests. Two epibenthic amphipods from the genus Melita were the most sensitive species to aqueous copper and zinc, with a 96-h LC50 value of 120 microg Cu/l for both M. awa and M. plumulosa juveniles, and a 96-h LC50 value of 640 microg Zn/l for juveniles of M. plumulosa. Juvenile amphipods (7-d old) were more sensitive than adult amphipods (>30-d old) in both water-only and whole-sediment tests, with adult-LC50/juvenile-LC50 ratios in water-only tests ranging from 1.2 to l.5 for copper and 1 to 1.4 for zinc. All species except C. colo, C. cf. lucasi and M. matilda were sensitive to the copper-spiked sediment, with survival between 14% and 74% of controls. Similarly, all species except C. colo and G. japonica, showed a response to the zinc-spiked sediment (26-81% of control survival). The epibenthic amphipods were more sensitive than the infaunal tube-dwelling amphipods and are recommended as test species.     

Equilibrium partitioning theory to predict the sediment toxicity of the anionic surfactant C(12)-2-LAS to Corophium volutator

The study of the effect of the sorption of linear alkylbenzene sulfonates (LAS) on the bioavailability to marine benthic organisms is essential to refine the environmental risk assessment of these compounds. According to the equilibrium partitioning theory (EqP), the effect concentration in water-only exposure will be similar to the effect concentration in the sediment pore water. In this work, sorption and desorption experiments with two marine sediments were carried out using the compound C₁₂-2-LAS. The effect of the sediment sorption on the toxicity of benthic organisms was studied in water-only and in sediment bioassays with the marine mud shrimp Corophium volutator. In addition, three common spiking methods were tested for its application in the toxicity tests, as well as the stability of the surfactant during the water-only and sediment-water test duration. LC50 values obtained from water-only exposure showed a good correspondence with the pore water concentrations calculated from the sorption and desorption isotherms in the spiked sediments.     

Toxicity of the mosquito control pesticide Scourge to adult and larval grass shrimp (Palaemonetes pugio)

This study investigated the toxicity of various concentrations of technical resmethrin and Scourge on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-h static renewal aqueous test without sediment, and a 24-h static nonrenewal aqueous test with sediment. For resmethrin, the 96-h aqueous LC50 value for adult shrimp was 0.53 microg/L (95% confidence interval (CI): 0.46-0.60 microg/L), and for larval shrimp was 0.35 microg/L (95% CI: 0.28-0.42 microg/L). In the presence of sediment, technical resmethrin produced a 24-h LC50 value for adult shrimp of 5.44 microg/L (95% CI: 4.52-6.55 microg/L), and for larval shrimp of 2.15 microg/L (95% CI: 1.35-3.43 microg/L). For Scourge, the 96-h aqueous LC50 for adult shrimp was 2.08 microg/L (95% CI: 1.70-2.54 microg/L), and for larval shrimp was 0.36 microg/L (95% CI: 0.24-0.55 microg/L). The 24-h sediment test yielded an LC50 value of 16.12 microg/L (95% CI: 14.79-17.57 microg/L) for adult shrimp, and 14.16 microg/L (95% CI: 12.21-16.43 microg/L) for larvae. Adjusted LC50 values to reflect the 18% resmethrin concentration in Scourge are 0.37 microg/L (adult), 0.07 microg/L (larvae) for the 96-h aqueous test, and 2.90 microg/L (adult), 2.6 microg/L (larvae) for the 24-h sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge.     

Lethal and sublethal effects of the pyrethroid, bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 microg/L (95% CI: 0.015-0.025 microg/L) and for larval shrimp was 0.013 microg/L (95% CI: 0.011-0.016 microg/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 microg/L (95% CI: 11.886-47.250 microg/L). The 24-h sediment LC50 for adult shrimp was 0.339 microg/L (95% CI: 0.291-0.381 microg/L) and for larval shrimp was 0.210 microg/L (95% CI: 0.096-0.393 microg/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.     

Use of reporter-gene based bacteria to quantify phenanthrene biodegradation and toxicity in soil

A phenanthrene-degrading bacterium, Sphingomonas paucimobilis EPA505 was used to construct two fluorescence-based reporter strains. Strain D harboring gfp gene was constructed to generate green fluorescence when the strain started to biodegrade phenanthrene. Strain S possessing gef gene was designed to die once phenanthrene biodegradation was initiated and thus to lose green fluorescence when visualized by a live/dead cell staining. Confocal laser scanning microscopic observation followed by image analysis demonstrates that the fluorescence intensity generated by strain D increased and the intensity by strain S decreased linearly at the phenanthrene concentration of up to 200 mg/L. Such quantitative increase and decrease of fluorescence intensity in strain D (i.e., from 1 to 11.90 ± 0.72) and strain S (from 1 to 0.40 ± 0.07) were also evident in the presence of Ottawa sand spiked with the phenanthrene up to 1000 mg/kg. The potential use of the reporter strains in quantitatively determining biodegradable or toxic phenanthrene was discussed.     

Toxicity of the mosquito control insecticide phenothrin to three life stages of the grass shrimp (Palaemonetes pugio)

Phenothrin is a synthetic pyrethroid used as a contact insecticide in mosquito control programs. This study compared the toxicity of phenothrin to adult, larval and embryonic grass shrimp (Palaemonetes pugio) and examined oxidative stress responses in adult and larval grass shrimp. The adult 24-h LC50 was 0.341 μg/L (95 % confidence intervals 0.282–0.412) and the 96-h LC50 was 0.161 μg/L (95 % CI 0.128–0.203 μg/L). The larval 24-h LC50 was 0.50 μg/L (95 % CI 0.441–0.568) and the 96-h LC50 was 0.154 μg/L (95 % CI 0.139–0.170 μg/L). In the presence of sediment, the 24-h LC50 was 6.30 μg/L (95 % CI 5.00–7.44 μg/L) for adults and 0.771 μg/L (95 % CI 0.630–0.944) for larvae. The sublethal biomarkers glutathione and lipid peroxidase (LPx) were examined after 96-h phenothrin exposure at five concentrations, and there were no statistically significant differences in these levels in adults or larvae compared to controls. There was a significant downward trend in larval LPx levels. This research confirms that phenothrin is highly toxic to grass shrimp and suggests that both adult and larval grass shrimp are appropriate life stages for risk assessments.     

Toxicity of the mosquito control insecticide phenothrin to three life stages of the grass shrimp (Palaemonetes pugio)

Phenothrin is a synthetic pyrethroid used as a contact insecticide in mosquito control programs. This study compared the toxicity of phenothrin to adult, larval and embryonic grass shrimp (Palaemonetes pugio) and examined oxidative stress responses in adult and larval grass shrimp. The adult 24-h LC50 was 0.341 μg/L (95 % confidence intervals 0.282-0.412) and the 96-h LC50 was 0.161 μg/L (95 % CI 0.128-0.203 μg/L). The larval 24-h LC50 was 0.50 μg/L (95 % CI 0.441-0.568) and the 96-h LC50 was 0.154 μg/L (95 % CI 0.139-0.170 μg/L). In the presence of sediment, the 24-h LC50 was 6.30 μg/L (95 % CI 5.00-7.44 μg/L) for adults and 0.771 μg/L (95 % CI 0.630-0.944) for larvae. The sublethal biomarkers glutathione and lipid peroxidase (LPx) were examined after 96-h phenothrin exposure at five concentrations, and there were no statistically significant differences in these levels in adults or larvae compared to controls. There was a significant downward trend in larval LPx levels. This research confirms that phenothrin is highly toxic to grass shrimp and suggests that both adult and larval grass shrimp are appropriate life stages for risk assessments.     

Correlations of Eisenia fetida metabolic responses to extractable phenanthrene concentrations through time

Eisenia fetida earthworms were exposed to phenanthrene for thirty days to compare hydroxypropyl-β-cyclodextrin (HPCD) extraction of soil and ¹H NMR earthworm metabolomics as indicators of bioavailability. The phenanthrene 28-d LC₅₀ value was 750 mg/kg (632-891, 95% confidence intervals) for the peat soil tested. The initial phenanthrene concentration was 319 mg/kg, which biodegraded to 16 mg/kg within 15 days, at which time HPCD extraction suggested that phenanthrene was no longer bioavailable. Multivariate statistical analysis of ¹H NMR spectra for E. fetida tissue extracts indicated that phenanthrene exposed and control earthworms differed throughout the 30 day experiment despite the low phenanthrene concentrations present after 15 days. This metabolic response was better correlated to total phenanthrene concentrations (Q² = 0.59) than HPCD-extractable phenanthrene concentrations (Q² = 0.46) suggesting that ¹H NMR metabolomics offers considerable promise as a novel, molecular-level method to directly monitor the bioavailability of contaminants to earthworms in the environment.     

Arsenic in groundwater and sediment in the Mekong River delta, Vietnam

A study of groundwater and sediment during 2007-2008 in the Mekong River delta in Vietnam (MDVN) revealed that 26%, 74%, and 50% of groundwater samples were above the US EPA drinking water guidelines for As (10 μg/L), Mn (0.05 mg/L), and Fe (0.3 mg/L). The range of As, Fe, and Mn concentrations in the MDVN were <0.1-1351 μg/L, <0.01-38 mg/L, and <0.01−14 mg/L, respectively. Elevated levels of As were found in groundwater at sampling sites close to the Mekong River and in wells less than 60−70 m deep. An inverse relationship was found between As and Mn concentrations in groundwater. Sediment samples from An Giang and Dong Thap had the highest As concentrations (18 mg/kg and 38 mg/kg, respectively). Arsenic sediment occurred mainly in the poorly crystalline Fe oxide phases. Reductive dissolution of the Fe oxide phase is not necessarily the dominant mechanism of As release to groundwater.     

Adverse effects of fullerenes (nC60) spiked to sediments on Lumbriculus variegatus (Oligochaeta)

Effects of fullerene-spiked sediment on a benthic organism, Lumbriculus variegatus (Oligochaeta), were investigated. Survival, growth, reproduction, and feeding rates were measured to assess possible adverse effects of fullerene agglomerates produced by water stirring and then spiked to a natural sediment. L. variegatus were exposed to 10 and 50 mg fullerenes/kg sediment dry mass for 28 d. These concentrations did not impact worm survival or reproduction compared to the control. Feeding activities were slightly decreased for both concentrations indicating fullerenes’ disruptive effect on feeding. Depuration efficiency decreased in the high concentration only. Electron and light microscopy and extraction of the worm fecal pellets revealed fullerene agglomerates in the gut tract but not absorption into gut epithelial cells. Micrographs also indicated that 16% of the epidermal cuticle fibers of the worms were not present in the 50 mg/kg exposures, which may make worms susceptible to other contaminants.     

Toxicity of the Mosquito Control Pesticide Scourge® to Adult and Larval Grass Shrimp (Palaemonetes pugio)

Abstract

This study investigated the toxicity of various concentrations of technical resmethrin and Scourge® on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-h static renewal aqueous test without sediment, and a 24-h static nonrenewal aqueous test with sediment. For resmethrin, the 96-h aqueous LC₅₀ value for adult shrimp was 0.53 μg/L (95% confidence interval (CI): 0.46–0.60 μg/L), and for larval shrimp was 0.35 μg/L (95% CI: 0.28–0.42 μg/L). In the presence of sediment, technical resmethrin produced a 24-h LC₅₀ value for adult shrimp of 5.44 μg/L (95% CI: 4.52–6.55 μg/L), and for larval shrimp of 2.15 μg/L (95% CI: 1.35–3.43 μg/L). For Scourge®, the 96-h aqueous LC₅₀ for adult shrimp was 2.08 μg/L (95% CI: 1.70–2.54 μg/L), and for larval shrimp was 0.36 μg/L (95% CI: 0.24–0.55 μg/L). The 24-h sediment test yielded an LC₅₀ value of 16.12 μg/L (95% CI: 14.79–17.57 μg/L) for adult shrimp, and 14.16 μg/L (95% CI: 12.21–16.43 μg/L) for larvae. Adjusted LC₅₀ values to reflect the 18% resmethrin concentration in Scourge® are 0.37 μg/L (adult), 0.07 μg/L (larvae) for the 96-h aqueous test, and 2.90 μg/L (adult), 2.6 μg/L (larvae) for the 24-h sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge® than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge®     

European risk assessment of LAS in agricultural soil revisited: species sensitivity distribution and risk estimates

Linear alkylbenzene sulphonate (LAS) is used at a rate of approximately 430,000 tons/y in Western Europe, mainly in laundry detergents. It is present in sewage sludge (70-5,600 mg/kg; 5-95th percentile) because of its high usage per capita, its sorption and precipitation in primary settlers, and its lack of degradation in anaerobic digesters. Immediately after amendment, calculated and measured concentrations are <1 to 60 mg LAS/kg soil. LAS biodegrades rapidly in soil with primary and ultimate half-lives of up to 7 and 30 days, respectively. Calculated residual concentrations after the averaging time (30 days) are 0.24-18 mg LAS/kg soil. The long-term ecotoxicity to soil microbiota is relatively low (EC10 >or=26 mg sludge-associated LAS/kg soil). An extensive review of the invertebrate and plant ecotoxicological data, combined with a probabilistic assessment approach, led to a PNEC value of 35 mg LAS/kg soil, i.e. the 5th percentile (HC5) of the species sensitivity distribution (lognormal distribution of the EC10 and NOEC values). Risk ratios were identified to fall within a range of 0.01 (median LAS concentration in sludge) to 0.1 (95th percentile) and always below 0.5 (maximum LAS concentration measured in sludge) according to various scenarios covering different factors such as local sewage influent concentration, water hardness, and sewage sludge stabilisation process. Based on the present information, it can be concluded that LAS does not represent an ecological risk in Western Europe when applied via normal sludge amendment to agricultural soil.     

Toxicity of water and sediment from stormwater retarding basins to Hydra hexactinella

Hydra hexactinella was used to assess the toxicity of stormwater and sediment samples from three retarding basins in Melbourne, Australia, using an acute test, a sublethal test, and a pulse test. Stormwater from the Avoca St retarding basins resulted in a LC50 of 613 ml/L, NOEC and LOEC values of 50 ml/L and 100 ml/L, while the 7 h pulse exposure caused a significant increase in the mean population growth rate compared to the control. Water samples from the two other retarding basins were found non-toxic to H. hexactinella. This is the first study to employ sediment tests with Hydra spp. on stormwater sediments and a lower population growth rate was observed for organisms exposed to sediment from the Avoca St retarding basins. The behavioral study showed that H. hexactinella tended to avoid the sediment-water interface when exposed to sediment from all retarding basins, compared to the reference sediment. Further work is needed to determine the long-term effects of stormwater polluted sediments and acute effects due to organism exposure to short-term high concentrations during rain events.     

Effects of the anti-fouling herbicide Irgarol 1051 on two life stages of the grass shrimp,Palaemonetes pugio

This study investigated lethal and sublethal effects (glutathione, lipid peroxidation, cholesterol, and acetylcholinesterase) of the anti-fouling herbicide Irgarol 1051 on larval and adult grass shrimp (Palaemonetes pugio). The 96-hour LC50 test for larvae resulted in an estimated LC50 of 1.52 mg/L (95% confidence interval [CI] 1.26–1.85 mg/L). The adult 96-h LC50 was 2.46 mg/L (95% CI = 2.07–2.93 mg/L). Glutathione, lipid peroxidation, cholesterol and acetylcholinesterase levels were not significantly affected in adult grass shrimp by exposure of up to 3.00 mg/L irgarol. Lipid peroxidation and acetylcholinesterase levels in the larvae were significantly higher than controls in the highest irgarol exposures of 1.0 and 2.0 mg/L, respectively. Cholesterol levels were significantly reduced in larvae in all four irgarol concentrations tested while glutathione levels were not significantly affected in larvae. Both lethal and sublethal effects associated with irgarol exposure were only observed at concentrations well above those reported in the environment.     

Effects of the anti-fouling herbicide Irgarol 1051 on two life stages of the grass shrimp, Palaemonetes pugio

This study investigated lethal and sublethal effects (glutathione, lipid peroxidation, cholesterol, and acetylcholinesterase) of the anti-fouling herbicide Irgarol 1051 on larval and adult grass shrimp (Palaemonetes pugio). The 96-hour LC50 test for larvae resulted in an estimated LC50 of 1.52 mg/L (95% confidence interval [CI] 1.26-1.85 mg/L). The adult 96-h LC50 was 2.46 mg/L (95% CI = 2.07-2.93 mg/L). Glutathione, lipid peroxidation, cholesterol and acetylcholinesterase levels were not significantly affected in adult grass shrimp by exposure of up to 3.00 mg/L irgarol. Lipid peroxidation and acetylcholinesterase levels in the larvae were significantly higher than controls in the highest irgarol exposures of 1.0 and 2.0 mg/L, respectively. Cholesterol levels were significantly reduced in larvae in all four irgarol concentrations tested while glutathione levels were not significantly affected in larvae. Both lethal and sublethal effects associated with irgarol exposure were only observed at concentrations well above those reported in the environment.     

Identification of a phytotoxic photo-transformation product of diclofenac using effect-directed analysis

The pharmaceutical diclofenac (DCF) is released in considerably high amounts to the aquatic environment. Photo-transformation of DCF was reported as the main degradation pathway in surface waters and was found to produce metabolites with enhanced toxicity to the green algae Scenedesmus vacuolatus. We identified and subsequently confirmed 2-[2-(chlorophenyl)amino]benzaldehyde (CPAB) as a transformation product with enhanced toxicity using effect-directed analysis. The EC₅₀ of CPAB (4.8 mg/L) was a factor of 10 lower than that for DCF (48.1 mg/L), due to the higher hydrophobicity of CPAB (log K_ow = 3.62) compared with DCF (log D_ow = 2.04) at pH 7.0.     

Lethal and sublethal effects of the pyrethroid,bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC₅₀ value for adult shrimp was 0.020 μ g/L (95% CI: 0.015–0.025 μ g/L) and for larval shrimp was 0.013 μ g/L (95% CI: 0.011–0.016 μ g/L). The 96-h aqueous LC₅₀ for adult sheepshead minnow was 19.806 μ g/L (95% CI: 11.886–47.250 μ g/L). The 24-h sediment LC₅₀ for adult shrimp was 0.339 μ g/L (95% CI: 0.291–0.381 μ g/L) and for larval shrimp was 0.210 μ g/L (95% CI: 0.096–0.393 μ g/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.     

Chronic toxicity of sediment-associated linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms

The toxicity of linear alkylbenzene sulphonates (LAS), to freshwater benthic organisms was assessed during exposure to spiked sediment. Lethal and sub-lethal end-points were monitored for two organisms (oligochaete Lumbriculus variegatus and nematode Caenorhabditis elegans). Results demonstrated relatively low toxicity (LOECs>100 mg/kg dry weight). No observed effect concentrations (NOECs) of 81 mg/kg dw (Lumbriculus) and 100 mg/kg dw (Caenorhabditis) were determined. For the oligochaete, no specific endpoint was particularly sensitive to LAS. For the nematode, egg production was the most sensitive endpoint. Significant degradation was measured over the 28-day duration of the Lumbriculus study, equating to a half-life of 20 days in sediment.     

Effects of Phos-Chek G75-F and Silv-Ex on red-winged blackbird (Agelaius phoeniceus) embryos

Effects of field application levels of wildfire control chemicals, Phos-Chek G75-F (PC) and Silv-Ex (SE), were examined on red-winged blackbird (Agelaius phoeniceus) embryos. Embryos were more sensitive to PC and SE when eggs were immersed for 10s at an early developmental stage (days 3-5 of incubation) than at a later stage (days 6-9 of incubation). The LC(50) (concentration causing 50% mortality) for early stage embryos exposed to PC was 213.3g/L (slope=1.6; 95% confidence interval [CI]=129.1-326.1). The no observed effect concentration (NOEC) was below 135g PC/L, which caused a significant increase in embryonic mortality and represents the lowest field coverage level of 1gal/100feet(2). The LC(50) for early stage embryos exposed to SE was 19.8g/L (slope=1.5; 95% CI=11.7-52.2). Significant mortality was observed at 10g SE/L and marginal at 7.5g SE/L with an apparent NOEC around 5g SE/L. Neither chemical resulted in apparent developmental malformations.     

Decamethylcyclopentasiloxane (D5) spiked sediment: Bioaccumulation and toxicity to the benthic invertebrate Hyalella azteca

Chronic toxicity and bioaccumulation of decamethylcyclopentasiloxane (D5) to Hyalella azteca was examined in a series of spiked sediment exposures. Juvenile H. azteca were exposed for 28 d (chronic) to a concentration series of D5 in two natural sediments of differing organic carbon content (O.C.) and particle size composition. The chronic, LC50s were 191 and 857 μg D5 g⁻¹ dry weight for Lakes Erie (0.5% O.C.) and Restoule (11% O.C.) respectively. Inhibition of growth only occurred with the L. Restoule spiked sediment with a resultant EC25 of 821 μg g⁻¹ dw. Lethality was a more sensitive endpoint than growth inhibition. Biota sediment accumulation factors (BSAFs, 28 d) were <1 indicating that D5 did not bioconcentrate based on lipid normalized tissue concentrations and organic carbon normalized sediment concentrations. Organic carbon (OC) in the sediment appeared to be protective, however normalization to OC did not normalize the toxicity. Normalization of D5 concentrations in the sediments to sand content did normalize the toxicity and LC50 values of 3180 and 3570 μg D5 g⁻¹ sand dw were determined to be statistically the same.